1. Field of the Invention
The present invention relates generally to a method and an apparatus for improving a service quality in a multimedia system, and more particularly to a method and an apparatus for reducing a deterioration of a Quality of Experience (QoE) in a multimedia service.
2. Description of the Related Art
In a Hypertext Transfer Protocol (HTTP)-based multimedia streaming service (hereinafter, referred to as a “multimedia service”), a stream is segmented in a unit of a predetermined time and a corresponding stream is transferred to a client in response to a client request. In this process, there is a limitation in decreasing a delay caused by initial buffering.
FIG. 1 illustrates a conventional fast forward operation in a HTTP-based multimedia service. Specifically, FIG. 1 illustrates that when a reproduction position within content is changed or content is changed during the use of the multimedia service, a delay is generated by buffering.
Referring to FIG. 1, T0 101 represents a time at which a fast forward is started and T1 103 represents a time at which the fast forward is completed in the multimedia service. A solid line 105 represents data before T0 101 and a solid line 107 represents data after T1 103. A dotted line represents a threshold 109 of a buffer. In order to start the reproduction of the multimedia, an amount of data that is larger than the threshold 109 of the buffer is required. Accordingly, when the amount of data in the buffer is larger than the threshold 109 before T0 101, and when the fast forward is started at T0 101 and then the fast forward is stopped at T1 103, the amount of data in the buffer decreases below the threshold 109.
Tb 111 represents a time required for the data in the buffer to reach the threshold 109. No multimedia is reproduced during Tb 111. Accordingly, Tb 111 is commonly referred to as a start-up delay, during which a user cannot receive the multimedia service. Consequently, a QoE of the service is deteriorated during Tb 111.
FIG. 2 illustrates an example of a delay according to a coding unit in a conventional multimedia service.
Referring to FIG. 2, when a random access occurs during an Inter (or Inter frame) 203 that is a unit image that cannot be independently decoded in a stream, a delay occurs until an Intra (or Intra frame) 201 appears that is a unit image that can be independently decoded in the stream. That is, a random access or a trick mode is available based on the unit image (Intra 201), which can be independently decoded.